The Physical, Chemical, Sensory Properties and Aromatic Organic Substance Profile of Kefir Added Citrus Fruits in Different Proportions

This study aims to increase the functionality of plain kefir by adding citrus fruits. Dry matter ratios of kefir samples ranged from 11.04 % to 11.75 %. The addition of fruit to kefir reduced the milk-fat ratios. The pH values of kefir samples ranged from 3.37 to 4.08 depending on fruit concentration. pH values also ranged from 3.37 to 4.08 depending on fruit concentration. Kefir samples containing grapefruit ( 37.5 %) had the lowest pH value (3.37) among the kefir samples. The viscosity of kefir samples at 20 rpm and 50 rpm at sliding speed ranged from 0.42 Pa.s to 2.88 Pa.s and from 0.31 to 1.60 Pa.s, respectively. The addition of fruit to plain kefir was reduced its viscosity. DPPH* of samples was between 1.21 and 38.93 % DPPH of samples with citrus fruit were statistically (p<0.01) higher than that of plain kefir samples. While adding orange to plain kefir samples reduced the amount of ethanol, adding grapefruit increased its amount, conversely. Plain kefir samples had higher acetic acid, butanoic acid, hexanoic acid, octanoic acid, n-decanoic acid, benzoic acid, benzaldehyde, benzaldehyde (2,5 bis), silanediol dimethyl, and benzyl alcohol ratios than that of orange, mandarin and grapefruit samples. However, the dlimonene, 1-methyl benzene and benzene 2-ethyl-1,3-dimethyl ratios of kefir samples containing orange, mandarin and grapefruit increased significantly compared to plain kefir. Panelists preferred orange (23 % and 37.5 %) and mandarin (37.5 %) kefir samples more than the others. Panelists gave lower scores to grapefruit-added samples than the other kefir samples.